Submarine, subterranean, and aerial telephony.



APPLICATION FILED MAY 12. 1916.'

Patent-ed Jan. 16, 1917.

UNITED STATES PATENT OFFICE.

REGINALD A. FESSENDEN, OF BROOKLINE, MASSACHUSETTS, ASSIGNOR TO SUBMARINE SIGNAL COMPANY, OF PORTLAND, MAINE, A CORPORATION OF MAINE.

Specification of Letters Patent.

Patented Jan. 16, 1917.

Application filed May 12, 1916. Serial No. 97,193.

To all whom it may concern Be it known that I, REGINALD A. FESSEN- DEN, of Brookline, in the county of Norfolk and State of Massachusetts, a citizen of the United States, have invented a new and useful Improvement in Submarine, Subterranean, and Aerial Telephony, of which the following is a specification.

This invention has for its object the increased efliciency of the transmission of impulses and more particularly of sound impulses, and still more particularly the transmission of speech through water as between submarines, through the ground as from a well in a fort to a ship in a nearby harbor, and through the air as in announcing trains in a large railway station.

Suitable apparatus and methods for accomplishing this are hereinafter set forth and claimed.

The figure accompanying this specification shows diagrammatically an apparatus for carrying out the invention.

In the figure 10 is a source of high frequency current, preferably above audibility, for example 100,000 cycles persecond, though as high as 1,000,000 may be used. Any suitable source may be used such for example as applicants high frequency dynamo shown in U. S. Patent No. 706,747, dated August 12, 1902, or there may be used applicants high frequency spark method as illustrated in U. S. Patent No. 706,742,

,dated August 12, 1902, or applicants quenched gap method shown in U. S. Patent No. 897,279, dated September 1, 1908, or any other methods for generating high frequency currents.

11, 13 are the windings of a magnetic amplifier of the type shown in applicants said U. S. Patent No. 706,747 and in his U. S. Patent No. 1,154,750, dated September 28, 1915, or the modified forms shown by Alexanderson, General E Zectric Review, March 1916. Either form may be used. In the form shown in my Patent No. 706,747 an iron core is used. In the form shown in my Patent No. 1,154,750 an iron core is preferably used, while in other forms, for example, that of my Patent No. 1,196,938, an iron core is not necessary. With this latitude in its construction I have shown merely the windings of the amplifier. Its construction in the circuits will be understood by those skilled in the art. The terminals of 11 are connected to the high frequency source 10 and to the variable condenser 12. One terminal of 13 is connected to the battery 15 and the other to the two-way switch 16 used for connecting either of the two transmitters 18, 19, in circuit with the battery 15, as desire 17 is a rectifier of any of the usual types. For the purpose of this invention any one of the now well known rectifiers may be used, being equivalents for each other.

20 is an oscillator of the type shown in U. S. Patent No. 1,167,366, dated January 4, 1916, the central rod 21 being attached to a vibrating member. This vibrating member has preferably a natural period of about 700 and when made in very large sizes preferably comprises a beam girder 23 designed to possess as little weight as possible but great stiflness, so that when the girder 23 is held at the two points of support 24, 25 to which it is attached, and rod 21 attached to its center, it will on being set in motion vibrate with a natural period of about 1,000. I preferably attach to the girder a disk of ght material 26to act as a diaphragm surface of such size, best found by experiment, that its inertia and damping will bring the natural period of the beam disk diaphragm so formed down to about 7 00, and will make the system almost dead-beat. In this way large diaphragms, say 50 feet square, may be made which will, on being set into operation by the oscillator, give very clear and articulate speech, and so loudly as to be heard a long distance in the air. Or if a steel diaphragm is used speech may be transmitted through water for a still longer distance. One terminal of the oscillator 20 is attached to the rectifier; the other to the source of high frequency currents 10.

The method of operation is as follows: The alternator 10 generates say 100 kw. of high frequency electrical energy. The circuit being tuned by the condenser 12 to the desired frequency, on speaking into the transmitters 18 or 19 the inductance of the main circuit is varied and the current also varied because of this change in inductance. As only a change of a few watts in the transmitter circuit makes a variation of several kilowatts in the main circuit, very powerful fluctuations of current corresponding to the voice, are generated 1n the main current. These would be unable to afi'ect any mag- .notic mechanism so as to produce an audible sound on account of their beingabove audibility, but on being transformed into direct currents by the rectifier 17 they can flow into the oscillator 20. This oscillator is by its nature peculiarly adapted to cooperate with the rest of the system, as it has no appreciable self-induction. And thereby the combination of a source of ultra-audible fre quency, a circuit of an amplifier circuit cartying the main ultra-audible frequency current, circuit tuning device, rectifier, noninductive electromagnetic motor, together with the second circuit of the amplifier actuated by a telephone transmitter is uniquely adapted for transmitting speech of great intensity through water or the earth or air.

The telephone transmitter 18 may be of the usual type, and the telephone transm tter 19 of the electrostatic type shown 1n said U. S. Patent No. 7 06,7 47 i or any other suitable type. If of the electromagnetic type the battery 15 may be omitted.

What I claim as my invention is 1. A tuned circuit comprising a source of ultra audible high frequency current, a rectifier, an electromagnetic mechanism adapted to produce audible sounds and an substantially no self-induction adapted to produce audible sounds and an amplifier having two windings, one winding of said ampli er being in said tuned circuit and a telephone transmitter in circuit with the other winding of the amplifier.

3. A tuned circuit comprising a source of ultra-audible high frequency current, a variable condenser, a rectifier, an electromagnetic mechanism adapted to produce audible sounds and an amplifier having two windings, one winding of said amplifier being in said tuned circuit and a telephone transmitter in circuit with the other winding of the amplifier.

4. A tuned circuit comprising a source of ultra-audible high frequency current, a variable condenser, a rectifier, an electromagnetic mechanism of substantially no sel -induction adapted to produce audible sounds and an amplifier having two windings, one winding of said amplifier being in said tuned circuit and a telephone transmitter in circuit with the other winding of the amplifier.

5. A tuned circuit comprising a source of ultra-audible high frequency current, a

- variable condenser, a rectifier, an electroma etic mechanism adapted to produce au 'ble sounds and an amplifier having two windings, one winding of said amplifier being in said tuned circuit and a telephone transmitter in circuit with the other winding of the amplifier, and means connected to, and adapted to be vibrated by said electromagnetic mechanism.

in said tuned circuit and a telephone transmitter in circuit with the other winding of the amplifier, and means connected to, and adapted to be vibrated by said electromagnetic mechanism.

7. A tuned circuit comprising a source of ultra-audible high frequency current, a variable condenser, a rectifier, an electromagentic mechanism adapted to produce audible sounds and an amplifier having two windings, one winding of said amplifier being in said tuned circuit and a telephone transmitter in circuit with the other Winding of the amplifier, and means connected to, and adapted to be vibrated by said electromagnetic mechanism, said means comprising a diaphragm.

8. A tuned circuit comprising a source of ultra-audible high frequency current, a variable condenser, a rectifier, an electroma etic mechanism of substantially no sel -induction adapted to produce audible sounds and an amplifier having two windings, one winding of said amplifier being in said tuned circuit and a telephone transmitter in circuit with the other winding of the amplifier, and means connected to, and adapted to be vibrated by said electromagnetic mechanism, said means comprising a diaphragm.

9. A tuned circuit comprising a source of ultra-audible high frequency current, a variable condenser, a rectifier, an electromagnetic mechanism adapted to produce audible sounds and an amplifier having two windings, one winding of said amplifier being in said tuned circuit and a telephone transmitter in circuit with the other winding of the amplifier, and means connected to, and adapted to be vibrated by said electromagnetic mechanism, said means comprising a stiff girder capable of a high period of vibration and a diaphragm attached thereto whereby the natural period of vibration of the two will be less than the vibration of said girder and the system will be substantially dead-beat.

10. A tuned circuit comprising a source of ultra-audible high frequency current, a variable condenser, a rectifier, an electromagnetic mechanism of substantially no self-induction adapted to produce audible sounds and an amplifier having two Windings, one winding of said amplifier being in said tuned circuit and a telephone transmitter in circuit with" the other Winding of the amplifier, and means connected to, and adapted to be vibrated by said electromagnetic mechanism, said means comprising a still girder capable of a high period of vibration and a diaphragm attached thereto whereby the natural period of vibration of the two Will be less than the vibration of said girder and the system will be substantially dead-beat.

REGINALD A. FESSENDEN. 

